A. This procedure includes guidance on repointing
stone
masonry using lime mortar.

B. Repointing is the process of removing deteriorated
mortar
from a masonry joint and replacing old
mortar with new,
sound mortar.

C. This process is sometimes referred to as "tuck
pointing",
though "tuck pointing", is
actually a decorative
treatment rather than a method of repair.
True tuck
pointing is the process of adding a
finish layer of
mortar, occasionally tinted, to the
outer portion of a
newly laid joint.

D. Major reasons for mortar joint failures include:

1. Weathering action,

2. Settling,

3. Temperature cycles,

4. Poor original design and materials,
and

5. Lack of exterior maintenance.

E. See 01100-07-S for general project guidelines
to be
reviewed along with this procedure.
These guidelines
cover the following sections:

1. Safety Precautions

2. Historic Structures Precautions

3. Submittals

4. Quality Assurance

5. Delivery, Storage and Handling

6. Project/Site Conditions

7. Sequencing and Scheduling

8. General Protection (Surface
and Surrounding)

These guidelines should be reviewed
prior to performing
this procedure and should be followed,
when applicable,
along with recommendations from the
Regional Historic
Preservation Officer (RHPO).

F. For guidance on preparing lime mortar, see 04100-03-S.

1.02 SUBMITTALS

A. Manufacturers' literature describing packaged
items.

B. Source and screen analysis of bulk aggregate.

C. Mortar sample: Submit, for verification
and approval,
a sample of each type of mortar used,
in form of 6" long
by 1/2" wide sample strips of mortar
set in aluminum or
plastic channels.

1. Provide record of mortar mix,
composition and field
procedures to be followed.

1.03 QUALITY ASSURANCE

A. Mock-ups: Raking and Repointing Sample Work:

1. Test/Sample Area and RHPO
Approval:

a. Initially perform
sample joint raking and
repointing
on each of a 100 sq. ft. test of
stone,
brick, and terra cotta areas as
approved
by RHPO.

b. Demonstrate
proficiency with joint raking
tools
and ability to not damage masonry units
with
either hand or power tools.

c. Mix and cure
test batch of repointing mortar
and
place in joints; repeat test mix until
mortar
color is approved. Test mortar should
be
matched, dried and approved before placing
in
joints.

A. Environmental Conditions: Perform repointing
only when
the temperature is between 40 degrees
Fahrenheit and 80
degrees Fahrenheit. If the temperature
is below 40
degrees, the mortar sets too slowly,
and there is a good
chance of freezing before it fully sets.
If the
temperature is above 80 degrees, the
mortar will set too
quickly, and there is a strong chance
of excessive loss
of water prior to adequate setting.

PART 2---PRODUCTS

2.01 MANUFACTURERS

A. Repointing Tools: Available from good hardware
stores,
building material suppliers or mail-order
catalogues.

D. A professional pointer experienced in old masonry
is
required for any of the following areas
or conditions:

1. Chimneys need repointing

2. Window lintels must be rebuilt

3. Masonry is loose or missing

4. Work must be done from scaffolds
or extension
ladders

5. The original mortar joints
were "beaded"-tooled
with a raised, round-profiled
joint that projects
out from the wall

3.02 PREPARATION

A. Preparing the Joints:

1. Clean area of loose dirt and
debris using a stiff
bristle brush and remove
all extraneous fastenings
and devices.

2. Install necessary protection
of adjacent building
materials, property and
persons from joint cleaning
work and dirt.

3. Control dust and dirt from
raking work; dampen area
being worked; and use
curtains to limit spread of
dust from joint raking
and cutting operations.

B. Joint Cutting and Raking:

1. Cut and rake old mortar from
existing joints by
hand using a hammer and
chisel. NOTE: POWER
CHISELS AND POWER SAWS
SHOULD NOT BE USED.

2. Place the chisel in the center
of the joint and
pound it with a striking
hammer or "No-Bounce"
hammer until the mortar
disintegrates.

3. Rake out the loose material
to a depth of about 1
inch and never to a depth
less than their width.
Leave a clean, square
face at the back of the joint
to provide optimum contact
with the new mortar.

4. While raking out joints, remove
all metal fittings
such as nails, brackets
and clips on both
horizontal and vertical
surfaces.

5. Carefully clean out the prepared
face with a soft
or stiff bristle brush,
or blow the joints clean
with low-pressure compressed
air (40-60 psi).

6. Thoroughly flush out joint
with clean, clear water.

3.03 ERECTION, INSTALLATION, APPLICATION

A. Filling Joints:

1. Dampen masonry surfaces and
joints to control
suction and evaporation
before placing repointing
mortars.

NOTE: THERE SHOULD
BE NO FREE WATER PRESENT WHICH
MAY CAUSE VOIDS IN THE
MORTAR.

2. Using a pointing tool, push
the mortar into the
joint from a board and
iron with the maximum
possible pressure; The
mortar should be applied in
layers, each to a maximum
thickness of 3/8".

NOTE: THE POINTING
TOOL SHOULD BE ABOUT 1/16"
NARROWER THAN THE JOINT
BEING FILLED TO ACHIEVE
GOOD COMPACTION. IN
SOME CASES, THE JOINTS WILL BE
SO THIN THAT A STANDARD
POINTING TOOL WILL NEED TO
BE GROUND DOWN TO FIT
THE JOINT.

3. Thoroughly compact each layer
of mortar and allow
to set until thumb-print
hard before applying the
next layer of mortar.

4. Fill the joints so that they
are slightly recessed
from the masonry face.
Avoid leaving a joint which
is visually wider than
the actual historical
appearance.

5. Continuously keep all excess
and spilled mortar
brushed off the faces
of masonry units, ledges and
other surfaces before
it sets or stains the work.

B. Joint Finishing:

1. Begin when mortar attains
"thumb print" hardness.

2. Tool the joint to match the
old mortar.

NOTE: IT IS IMPORTANT
TO TOOL THE JOINT AT THE
RIGHT STAGE; IF THE JOINT
IS TOO SOFT, THE COLOR
WILL BE LIGHTER THAN
EXPECTED AND HAIRLINE
SHRINKAGE CRACKS ARE
LIKELY TO OCCUR; IF THE JOINT
IS TOO HARD WHEN TOOLED,
DARK STREAKS MAY APPEAR
(TOOL BURNING) AND GOOD
CLOSURE OF THE MORTAR
AGAINST THE MASONRY WILL
NOT BE ACHIEVED.
EXCESSIVE TOOLING MAY
BRING LIME AND FINE
AGGREGATES TO THE SURFACE,
CREATING A VISUAL CHANGE
IN THE TEXTURE AND A
SURFACE SUBJECT TO EARLY
DETERIORATION.

3. To produce a roughened texture,
lightly spray the
mortar with water after
the initial set, stipple
the mortar with a stiff
bristle brush or dab the
mortar with coarse sacking.

4. Protect finished work from
direct sun and rain
until the face has dried
and hardened.

3.04 ADJUSTING/CLEANING

A. Cleaning Up:

1. Use masking and drop cloths
to prevent mortar
stains on adjacent work
and ledges.

2. Keep work areas clean and
free from mortar drips,
spills and residue of
waste mortars or wash-off.

3. Clean off excess mortar as
work proceeds using
masonry brushes before
mortar sets.

4. Wash completed repointing
work when finished mortar
joints are set with clean
water and masonry
brushes, scrubbing only
as required to clean mortar
stains off masonry without
scouring the units and
joint faces.

5. Do not use acid or detergent
cleaning agent to aid
mortar removal and clean-up
without written
approval from RHPO.

B. Curing:

1. Schedule work only when moderate
weather is
forecast.

2. Protect completed work from
adverse weather, heavy
rainfall, freezing, and
drying by direct sunlight
and winds until cured.

3. Sprinkle or mist repointed
work as required to
achieve cure in mortar
joints for a minimum of 72
hours after completion.

4. Lime Mortar: Cures by
drying and crystallization,
not by hydration; and
can be washed out of joints
if not protected before
it cures.

NOTE: USE OF METAL
SCRAPERS OR BRUSHES IS NOT
PERMITTED. USE
OF ACID OR ALKALI CLEANING AGENTS
IS NOT PERMITTED.

D. Some efflorescence, called new construction "bloom,"
occasionally appears on the surface
within the first few
months following a repointing project.
These deposits
normally are harmless and are removed
by the natural
washing of the rain. If not removed
by natural
weathering, they can be removed with
dry brushing with a
bristle brush. The use of chemical
cleaners to remove
this type of efflorescence normally
is not necessary;
AVOID USING ACIDS, PARTICULARLY MURIATIC
ACID.